Under normal atmospheric conditions, an adherent and resistant durable surface layer builds up on the top surface of ungalvanized copper and develops further, after the passage of time, into a uniform brown color, because of the reaction of the copper with moisture and/or atmospheric oxygen.
However, for the different applications, particularly in the construction field, the request is often made for decorative, dull-silver-colored surfaces, which are resistant under conditions such as exposure to weather or a treatment with chemical solutions. It is furthermore intended that the appearance of the top surface will not change substantially due to handling during installation nor due to exposure to weather.